Title: Growth and physiology of woody plants in response to elevated CO{sub 2} and defoliation in an open-top field study

Abstract

Seedlings of sugar maple (Acer saccharum) and trembling aspen (Populus tremuloides) were exposed for an entire growing season to ambient (-357 {mu}mol mol{sup -1}) or elevated ({approximately}650 {mu}mol mol{sup -1}) levels of CO{sub 2}. To simulate natural defoliation, a subset of the seedlings within each CO{sub 2} treatment also had 50 % of their foliage clipped in late June. During the growing season there were three sequential harvests. The first was coincident with defoliation, followed by a mid-season harvest in early August and a final harvest after leaf senescence. Allocational, morphological and physiological determinants of growth were measured at each harvest. This is the first of two years of CO{sub 2} exposure, and preliminary analyses indicate an increase in both photosynthesis and growth for trembling aspen and sugar maple. However, after accounting for initial growth differences, the magnitude of this enhancement appears to have diminished over the course of the growing season, which can largely be explained by changes in physiological response. Interestingly, there was no growth {open_quotes}acclimation{close_quotes} to an enriched-CO{sub 2} environment for sugar maple seedlings that had been artificially defoliated.

@article{osti_95901,
title = {Growth and physiology of woody plants in response to elevated CO{sub 2} and defoliation in an open-top field study},
author = {Volin, J.C. and Kruger, E.L. and Lindroth, R.L.},
abstractNote = {Seedlings of sugar maple (Acer saccharum) and trembling aspen (Populus tremuloides) were exposed for an entire growing season to ambient (-357 {mu}mol mol{sup -1}) or elevated ({approximately}650 {mu}mol mol{sup -1}) levels of CO{sub 2}. To simulate natural defoliation, a subset of the seedlings within each CO{sub 2} treatment also had 50 % of their foliage clipped in late June. During the growing season there were three sequential harvests. The first was coincident with defoliation, followed by a mid-season harvest in early August and a final harvest after leaf senescence. Allocational, morphological and physiological determinants of growth were measured at each harvest. This is the first of two years of CO{sub 2} exposure, and preliminary analyses indicate an increase in both photosynthesis and growth for trembling aspen and sugar maple. However, after accounting for initial growth differences, the magnitude of this enhancement appears to have diminished over the course of the growing season, which can largely be explained by changes in physiological response. Interestingly, there was no growth {open_quotes}acclimation{close_quotes} to an enriched-CO{sub 2} environment for sugar maple seedlings that had been artificially defoliated.},
doi = {},
journal = {Bulletin of the Ecological Society of America},
number = 2,
volume = 76,
place = {United States},
year = 1995,
month = 6
}

Patterns of UC-photosynthate distribution in growth chamber-grown Populus xeuramericana cv. Negrito de Granada were determined 24 h, 3 weeks, and 5 weeks after defoliation in the developing leaf zone. Translocation patterns were determined by exposing leaves below, within, or above the defoliated zone to UCO2 and determining UC distribution within the plant after 48 h. Translocation patterns were altered within 24 h after defoliation. When leaves below or remaining tissue of leaves within the zone of defoliation were exposed to UCO2, a greater percentage of UC-photosynthate was transported to the expanding shoot and lateral branches and less to the rootsmore » in defoliated plants compared to controls. Little difference between defoliated and control plants and UC distribution occurred when new leaves produced subsequent to defoliation were exposed to UCO2. By 5 weeks after defoliation there was little difference in patterns of UC distribution between defoliated and control plants. These results substantiate biomass partitioning data which showed that a single defoliation of young poplar plants did not affect diameter or height growth, whereas leaf growth was stimulated and root growth reduced.« less

A comparison was made of the nature and severity of symptoms developed on ozonated bean plants (Phaseolus vulgaris) grown in a greenhouse, growth chamber, and open-top chamber. Data show that a significant difference occurs in the ozone response of greenhouse and growth chamber plants compared to open-top chamber plants both in respect to symptom and sensitivity. It was concluded that results obtained in greenhouse studies cannot be extrapolated to the field; therefore their usefulness in setting ambient air standards should be questioned. A further question was raised as to why bean plants which are relatively sensitive to single high dosesmore » of ozone develop definite toxicity symptoms with continuous exposure to low concentrations of the pollutant. Preliminary evidence indicates that continuous low levels of oxidant predispose a plant to injury. There is also the possibility that a second pollutant acts synergistically with ozone to produce the observed damage.« less

Autumn olive and cherry olive plants can be established on acidic to neutral flyash disposal areas. European black alder grows rapidly, but overall survival is poor. Sawtooth oak survives well, but early growth is slow. Sycamore and shrub dogwoods show fair to moderate survival, but dieback and poor early growth are common. Application of 10 cm of subsoil to flyash before revegetation appears to reduce erosion but does not significantly improve survival or growth of woody plants. Interactions of trace metals in plants and substrates are exceedingly complex. Metal accumulation in the woody plants grown on flyash is discussed. (18more » references, 5 tables)« less

Growth, biomass, and survival of bald cypress (Taxodium distichum (L.) Richard), water tupelo (Nyssa aquatica L.), black willow (Salix nigra Marshall), and button bush (Cephalanthus occidentalis L.) were examined in a 3 {times} 3 factorial experiment varying water temperatures (Ambient, mid, and high ({approximately} 40 C)) and water levels (drained, saturated, and flooded). Stem diameter and height, biomass, and survivorship for water tupelo and bald cypress were all reduced by the high/flooded treatment. Black willow growth had the greatest variability among nonlethal flooding and temperature treatments, and achieved the greatest biomass of the four species. In the high/flooded treatment, however,more » only 47% of the black willow seedlings survived and stem diameter, height, and biomass of survivors were greatly reduced. Button bush had intermediate variability of growth to the nonlethal treatments as compared to the other study species. Survival of button bush seedlings in the high/flooded treatment was high (87%), but root biomass of the survivors was reduced. Interspecific differences in growth, biomass, survivorship, and morphological characteristics existed among these swamp species to experimental conditions. These responses may help explain vegetation patterns in a thermally impacted swamp.« less